To automatically control the thawing of said food, microwave ovens are currently provided with weight sensors which measure the weight variation of the food during said thawing. These sensors are connected to a control member or microprocessor which, based on a prearranged program and the data obtained by the sensor, halts the operation of the microwave generator and consequently the thawing when the weight of the food has attained a predetermined value.
As an alternative to the aforesaid there are microwave ovens provided with infrared sensors which measure the surface temperature of the food. The sensors, connected to a microprocessor, cause the control member to act on the microwave generator and halt its operation when the food surface temperature has reached a predetermined value.
In both cases, a microwave oven as described is costly and laborious to construct. In addition, the data obtained by said sensors do not always reflect the true thawing level attained by the food, particularly with regard to its interior.